EP2918939B1 - Filter cartridge for a safety workbench and safety workbench with at least one filter cartridge - Google Patents

Filter cartridge for a safety workbench and safety workbench with at least one filter cartridge Download PDF

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Publication number
EP2918939B1
EP2918939B1 EP15000740.9A EP15000740A EP2918939B1 EP 2918939 B1 EP2918939 B1 EP 2918939B1 EP 15000740 A EP15000740 A EP 15000740A EP 2918939 B1 EP2918939 B1 EP 2918939B1
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EP
European Patent Office
Prior art keywords
filter cartridge
filter
filter body
cartridge according
projection
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
EP15000740.9A
Other languages
German (de)
French (fr)
Other versions
EP2918939A3 (en
EP2918939B8 (en
EP2918939A1 (en
Inventor
Thomas Hinrichs
Sven Gragert
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Berner International GmbH
Original Assignee
Berner International GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Berner International GmbH filed Critical Berner International GmbH
Priority to PL15000740T priority Critical patent/PL2918939T3/en
Publication of EP2918939A1 publication Critical patent/EP2918939A1/en
Publication of EP2918939A3 publication Critical patent/EP2918939A3/en
Publication of EP2918939B1 publication Critical patent/EP2918939B1/en
Application granted granted Critical
Publication of EP2918939B8 publication Critical patent/EP2918939B8/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B01D46/2403—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
    • B01D46/2411—Filter cartridges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/0039—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours with flow guiding by feed or discharge devices
    • B01D46/0041—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours with flow guiding by feed or discharge devices for feeding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B01D46/2403—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
    • B01D46/2411—Filter cartridges
    • B01D46/2414—End caps including additional functions or special forms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B15/00—Preventing escape of dirt or fumes from the area where they are produced; Collecting or removing dirt or fumes from that area
    • B08B15/02—Preventing escape of dirt or fumes from the area where they are produced; Collecting or removing dirt or fumes from that area using chambers or hoods covering the area
    • B08B15/023—Fume cabinets or cupboards, e.g. for laboratories
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/28—Arrangement or mounting of filters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
    • F24F3/12—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling
    • F24F3/16—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by purification, e.g. by filtering; by sterilisation; by ozonisation
    • F24F3/163—Clean air work stations, i.e. selected areas within a space which filtered air is passed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F8/00—Treatment, e.g. purification, of air supplied to human living or working spaces otherwise than by heating, cooling, humidifying or drying
    • F24F8/10—Treatment, e.g. purification, of air supplied to human living or working spaces otherwise than by heating, cooling, humidifying or drying by separation, e.g. by filtering
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F8/00—Treatment, e.g. purification, of air supplied to human living or working spaces otherwise than by heating, cooling, humidifying or drying
    • F24F8/10—Treatment, e.g. purification, of air supplied to human living or working spaces otherwise than by heating, cooling, humidifying or drying by separation, e.g. by filtering
    • F24F8/108—Treatment, e.g. purification, of air supplied to human living or working spaces otherwise than by heating, cooling, humidifying or drying by separation, e.g. by filtering using dry filter elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2271/00—Sealings for filters specially adapted for separating dispersed particles from gases or vapours
    • B01D2271/02—Gaskets, sealings
    • B01D2271/022—Axial sealings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
    • B01L1/00—Enclosures; Chambers
    • B01L1/04—Dust-free rooms or enclosures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
    • B01L2300/00—Additional constructional details
    • B01L2300/06—Auxiliary integrated devices, integrated components
    • B01L2300/0681—Filter

Definitions

  • the invention relates to a filter cartridge for a safety workbench according to the preamble of claim 1 and a safety workbench according to the preamble of claim 13.
  • Safety cabinets are used, among other things, in the pharmaceutical and biotechnological field when handling working materials that have a high risk potential. These substances include infectious, carcinogenic, mutagenic or fertile substances, including hazardous substances.
  • Safety cabinets usually have a working opening on their front through which an operator sitting in front of the safety cabinet can insert their hands and forearms into a working area of the safety cabinet in which the working materials are located.
  • a glass pane is arranged in front of the work opening, which offers the operator a good view of the working materials in the interior or work space.
  • ambient air is sucked into the interior of the safety workbench through the work opening. The resulting air flow prevents any contaminated air from the interior from getting into the environment and thus ensures personal protection.
  • the supplied ambient air is circulated with a part of the air inside the safety workbench by means of a blower before it comes into contact with the working materials and is thereby cleaned with filters.
  • a safety workbench in which the filters are designed as cartridge filters and are equipped with a plurality of filter cartridges of the type mentioned at the beginning which are arranged next to one another.
  • These filter cartridges consist of a hollow cylindrical filter body, which surrounds an interior of the filter cartridge in the radial direction, an open cover encapsulated with an upper end of the filter body, which surrounds an inflow opening opening into the interior, and a closed cover encapsulated with a lower end of the filter body.
  • the ambient air sucked in through the working opening and the air circulated in the safety workbench first flow through the inflow opening into the interior of the filter cartridge and from there pass through the filter body or the filter material, the air being cleaned.
  • the cartridge filters are so-called micro or HEPA filters.
  • the GB 2 261 830 A. already discloses a filter cartridge according to the preamble of claim 1.
  • the projection there has no fluidic function, but only enables the attachment of a pull rod.
  • the inflow surface of the projection comprises on its upper side an annular surface perpendicular to the longitudinal center axis of the filter cartridge and a recessed conical surface surrounded by it, which together form at least half of the inflow surface.
  • This leads to considerable turbulence and thus to a decrease in the kinetic energy of the air flow, which reduces the amount of air flowing through the filter material at the same pressure drop across the filter material.
  • the flow speed at the upper end of the projection increases abruptly because of the reduction in the flow cross section, so that fewer particles carried by the air flow are deposited on the inside of the filter body, which leads to an uneven filter effect.
  • the object of the invention is to improve a filter cartridge of the type mentioned at the outset for use in a safety workbench in such a way that without affecting the filter action and without changing the filter material of the filter cartridges used in safety workbenches, the flow rate of the through the filter body or the filter material flowing air can be enlarged.
  • the inflow surface on the inside of the tapered projection projecting inward beyond the closed cover is coaxial and rotationally symmetrical to the longitudinal center axis of the filter cartridge and the filter body in order to deflect the air evenly on all sides.
  • a reduction in the pressure difference between the inflow side and the outflow side of the filter cartridge is achieved above all if the inflow opening has, according to the invention, a nozzle-like flow cross section which decreases in the direction of the interior, while an increase in the flow rate, i.e. the amount of air flowing through the filter body per unit of time, through the decrease in the flow cross-section of the inflow opening in the direction of the interior according to the invention and through the tapered projection which projects according to the invention on the closed cover towards the inflow opening into the interior.
  • the open cover is preferably designed such that the flow cross-section of the inflow opening already decreases outside the filter body or in the direction of flow of the air before reaching the filter body, so that the entire length of the filter body can be used for air filtering without the air inside the filter body or must be redirected behind the inflow opening against the inflow direction.
  • the ratio between the smallest flow cross section at an inner end of the inflow opening and the largest flow cross section at an outer end of the inflow opening is less than 0.75 and preferably less than 0.5, so that the air inside the inflow opening is like is accelerated in a nozzle. It is believed that this acceleration is one of the causes of the increase in volume flow through the filter cartridge.
  • the flow cross-section is advantageously reduced over a relatively short distance, the length of which is expediently less than one tenth of the length of the filter cartridge, so that the nozzle-like inflow opening requires little space within the housing of the safety workbench.
  • a further expedient embodiment of the invention provides that the inflow opening at its inner end is delimited by a hollow cylindrical short web coaxial with the longitudinal central axis of the filter cartridge, which protrudes a little into the interior of the filter body and delimits a flat groove which is open towards the filter body and in which the adjacent front end of the filter body can be shed.
  • the groove is also delimited on the outside by a web which is coaxial with the longitudinal center axis of the filter cartridge and which surrounds the outer peripheral surface of the filter body at its adjacent end face.
  • the open cover of the filter cartridge advantageously has an edge flange which projects beyond the outer circumference of the filter body in the radial direction of the longitudinal center axis.
  • An annular projection which surrounds the inflow opening outside the filter cartridge and delimits it in the radial direction, expediently projects over the side of the edge flange facing away from the filter body.
  • the edge flange and the hollow annular projection which is expedient to save material, are advantageously made of thermoplastic plastic, in order thereby to give the inflow opening a desired contour in a simple manner.
  • the open cover can be made in one piece or in several parts, the edge flange and the projection preferably being integral parts of the open cover in the first-mentioned case.
  • the inflow opening preferably has a rotationally symmetrical boundary surface which is coaxial with a longitudinal center axis of the filter cartridge and the filter body and whose angle of inclination increases in the direction of flow of air through the inflow opening.
  • the outside diameter of the inflow surface on a foot of the projection facing away from the inflow opening is somewhat smaller than the inside diameter of the filter body, so that part of the air flows past the projection to the very end of the filter body and the filter body is thus used over its entire length for air filtering can be.
  • the closed cover and the projection are also advantageously formed in one piece from thermoplastic material, the projection on the outside of the closed cover expediently delimiting a depression with a shape corresponding to the shape of the projection, so that the closed cover is as thin-walled as possible over its entire diameter and thus can be trained to save material.
  • the filter body between the open and the closed lid can be surrounded by an air-permeable handle protection, which during handling Prevents contact with the filter body.
  • the safety workbench 10 shown in the drawing and intended for handling carcinogenic, mutagenic or fertility-endangering or pathogenic working substances essentially consists of a height-adjustable lower part or base frame 12 and an upper part 14 with a housing 16 which surrounds a working space 18 serving for handling the working substances .
  • the work area 18 is delimited on a front side of the safety workbench 10 by a glass pane 20 which allows an operator (not shown) sitting in front of the safety workbench 10 to have a good view of the work space 18.
  • a glass pane 20 which allows an operator (not shown) sitting in front of the safety workbench 10 to have a good view of the work space 18.
  • Below the glass pane 20 is an elongated slot-like working opening 22 through which the operator can handle it can introduce their forearms and hands into the work area 18 with the working materials.
  • the upper part 14 of the housing 16 contains, among other things, a blower 24, two HEPA filters 26 and 28 arranged above the working space 18, and six HEPA filters 30 arranged below the working space 18.
  • a channel-shaped suction opening 32 is arranged on the underside of the working space 18 immediately behind the working opening 22, which, like the glass pane 20 and the working opening 22, are arranged in the Extends essentially over the entire width of the safety workbench 10.
  • the suction opening 32, as well as further suction openings (not shown) arranged at the bottom of the work space 18, are connected by a plenum 34 to the inlet or unfiltered air side 36 of the HEPA filter 30, the outlet or clean air side 38 thereof by a suction channel 40 on the rear side of the housing 16 is connected to the suction side of the fan 24.
  • the fan 24 generates a slight negative pressure in the plenum 34 through the filters 30, as a result of which air is drawn in from the surroundings and from the working space 18 through the working opening 22 into the channel-shaped suction opening 32, as indicated by the arrows A in Fig. 1 shown.
  • the sucked-in air then flows through the filters 30 and the suction channel 40 to the blower 24. From there, part of the air is blown through the HEPA filter 26 from above into the working space 18, where the air flows down along the glass pane 20, as by arrows B in Fig. 1 shown. Another part of the air is through one above the fan 24 and the HEPA filter 28 on the top of the upper part 14 arranged exhaust air connection 39 discharged from the upper part 14 of the safety workbench 10, as indicated by the arrows C in Fig. 1 shown.
  • the HEPA filters 30 are cartridge filters which are arranged next to one another in a filter housing 44 which is wedge-shaped in cross section and extends over the entire width of the safety workbench 10.
  • the filter housing 44 is delimited towards the plenum 34 by an inclined intermediate wall 42 with six circular openings.
  • An exchangeable filter cartridge 46 is inserted into each of the openings from above, which protrudes obliquely downward into an interior of the filter housing 40 that communicates with the suction channel 40.
  • each filter cartridge 46 consists of a hollow cylindrical filter body 48, an open cover 50 attached to the upper end of the filter body 48, a flat sealing element 52 arranged between the filter body 48 and the cover 50, and a closed cover 54 attached to the lower end of the filter body 48.
  • the filter body 48 consists of a zigzag folded filter material which is shaped into a hollow cylinder and surrounds a cylindrical interior 56. The ends of the filter material that are parallel to the pleating are tightly connected to one another along a longitudinal adhesive seam. The opposite ends of the filter body 48 are sealed airtight with the open cover 50 and the sealing element 52 on the one hand and the closed cover 54 on the other hand.
  • the open cover 50 which is made of a thermoplastic material, is formed in one piece and has an integrated one on its side facing the filter body 48 Edge flange 60 provided.
  • the flat edge flange 60 which is perpendicular to a longitudinal center axis 66 of the filter cartridge 46 and the filter body 48, has a square outer contour.
  • a hollow annular projection 64 which surrounds an inflow opening 70 coaxial with the longitudinal center axis 66, projects beyond the upper side of the edge flange 60 facing away from the filter body 48.
  • the inflow opening 70 has a rotationally symmetrical boundary surface coaxial with the longitudinal central axis 66.
  • the boundary surface consists of three partial surfaces arranged one behind the other in the direction of flow.
  • the first partial surface is inclined at an angle of approximately 30 degrees and the second partial surface is inclined at an angle of approximately 45 degrees to a plane parallel to the edge flange 60, so that the angle of inclination of the partial surfaces increases in the direction of flow of air through the inflow opening 70.
  • edge flange 60 or the flat sealing element 52 arranged under the edge flange 60 abuts against the flat intermediate wall 42 from above after the filter cartridge 46 has been installed.
  • the edge flange 60 is screwed onto the intermediate wall 24 from above with four screws (not shown) passing through the sealing element 52.
  • the sealing element 52 has in each of its four corners a passage opening 80 for one of the fastening screws of the edge flange 60.
  • the inflow opening 70 delimited by the projection 64 has an interior 56 decreasing flow cross-section, so that the unfiltered air is accelerated when it enters the filter cartridge 46 as it passes through the inflow opening 70.
  • the height of the projection 64 and thus the length of the tapered nozzle-like inflow opening 70 is less than a tenth of the length of the filter cartridge 46 and is therefore relatively small.
  • the flow cross-section at the upper or outer end of the tapered inflow opening 70 is more than twice the smallest flow cross-section at the lower or inner end of the inflow opening 70, so that the inflowing air is greatly accelerated over a short distance.
  • the lower or inner end of the inflow opening 70 is delimited by a short annular hollow cylindrical web 72, which forms the third partial surface.
  • the web 72 protrudes a little into the interior 56 of the filter body 48 and forms the inner boundary of a flat groove 74 on the side of the open cover 50 or the filter element 52 facing the filter body 48, in which the upper front end of the filter body 48 is cast.
  • the upper boundary 76 of the groove 74 is formed by the sealing element 52, while the outer boundary of the groove 74 is formed by a short annular web 62 () projecting beyond the underside of the sealing element 52 Fig. 7 ) is formed.
  • cover 50 and the sealing element 52 can be produced in one piece as an integral component, in which case the groove 74 is delimited upwards by a closed bottom of the hollow projection 64, while its inner and outer delimitation is formed by short annular webs which follow project below the closed bottom of the hollow projection 64.
  • a flat seal (not shown) consisting of a foam material, which like the edge flange 60 has a square outer contour and a circular inner passage opening, the inside diameter of which is somewhat larger than the outside diameter of the filter body 48.
  • the closed cover 54 at the lower end of the filter body 48 also consists of a thermoplastic.
  • the one-piece cover 54 includes a hollow cylindrical outer peripheral edge 82 protruding towards the filter body 48 with an inner diameter corresponding to the outer diameter of the filter body 48, an annular flat bottom part 84 adjoining the peripheral edge 82 and providing a contact surface for the cover 54 encapsulated lower end of the filter body 48 forms, as well as a central, conical projection 86 tapering in the direction of the inflow opening 70, which protrudes a little into the interior 56 of the filter body 48.
  • the conical projection 86 On its inside, the conical projection 86 has an inflow surface 90 facing the inflow opening 70, which is inclined at an angle of approximately 45 degrees with respect to the annular flat base part 84 and also with respect to the longitudinal central axis 66 and is symmetrical to the longitudinal central axis 66.
  • the diameter at the foot of the conical projection 86 is somewhat smaller than the inside diameter of the filter body 48, so that part of the inflowing air can pass along the projection 86 to the lower end of the filter body 48.
  • the tip of the conical projection 86 can be slightly rounded, as in FIG Fig. 7 shown.
  • the height of the projection 86 is approximately one sixth to one seventh the length of the filter body 48.
  • the wall thickness of the closed cover 54 is the same over its entire diameter, so that the closed cover 54 on the outside or underside of the filter cartridge 46 has a conical depression corresponding to the projection 86 (not visible).
  • the protrusion 92 protruding into the interior 56 has the shape of a hemisphere, the pole of which faces the inflow opening 70 and the equator of which adjoins the annular, flat bottom part 84.
  • the height of the projection 92 and the diameter at its base correspond to that of the projection 86 from FIGS Figures 6 and 7 .
  • the protrusion 94 is like in the filter cartridge 46 in Fig. 7 conical, but protrudes considerably further into the interior 56, its height corresponding to about seven tenths of the length of the filter body 48.
  • the inclination of the inflow surface 90 on the inside of the projection 94 is therefore steeper than in the case of the filter cartridge 46 in FIG Fig. 7 , wherein the angle of inclination with respect to the annular flat bottom part 84 is approximately 80 degrees.
  • the tip of the projection 94 is rounded slightly convex.
  • the closed cover 54 does not have an inwardly projecting projection, but is aligned flat and perpendicular to the longitudinal central axis 66 of the filter cartridge 46.
  • the open cover 50 each has the same nozzle-like inflow opening 70 as in the filter cartridge 46 in FIGS Figures 4 to 7 on.
  • the filter material 48 is folded in a zigzag shape and shaped into a hollow cylinder Fig. 11
  • the filter cartridge 46 shown is additionally provided with an air-permeable handle guard 96 designed as a perforated cylinder, which surrounds the filter body 48 at a short distance from its outer circumference.
  • the opposite ends of the handle guard 96 are cast together with the respectively adjacent end of the filter body 48 in the groove 74 of the cover 50 or in the cover 54 and thereby firmly connected to the two covers 50, 54.
  • the handle guard 96 suitably consists of a thin-walled thermoplastic, but can also consist of a thin metal sheet.

Description

Die Erfindung betrifft eine Filterpatrone für eine Sicherheitswerkbank gemäß dem Oberbegriff des Anspruchs 1 und eine Sicherheitswerkbank gemäß dem Oberbegriff des Anspruchs 13.The invention relates to a filter cartridge for a safety workbench according to the preamble of claim 1 and a safety workbench according to the preamble of claim 13.

Sicherheitswerkbänke werden unter anderem auf pharmazeutischem und biotechnologischem Gebiet beim Umgang mit Arbeitsstoffen eingesetzt, die ein hohes Gefährdungspotential besitzen. Unter diesen Arbeitsstoffen finden sich infektiöse, cancerogene, mutagene oder fruchtbarkeitsgefährdende Stoffe, darunter auch Gefahrstoffe.Safety cabinets are used, among other things, in the pharmaceutical and biotechnological field when handling working materials that have a high risk potential. These substances include infectious, carcinogenic, mutagenic or fertile substances, including hazardous substances.

Sicherheitswerkbänke besitzen gewöhnlich an ihrer Vorderseite eine Arbeitsöffnung, durch die eine vor der Sicherheitswerkbank sitzende Bedienungsperson ihre Hände und Unterarme in einen Arbeitsraum der Sicherheitswerkbank einführen kann, in dem sich die Arbeitsstoffe befinden. Vor der Arbeitsöffnung ist eine Glasscheibe angeordnet, die der Bedienungsperson eine gute Sicht auf die Arbeitsstoffe im Innen- oder Arbeitsraum bietet. Um Bedienungspersonen und weitere Personen in der Umgebung der Sicherheitswerkbank vor einem Austritt von Arbeitsstoffen durch die Arbeitsöffnung zu schützen, wird Umgebungsluft durch die Arbeitsöffnung in den Innenraum der Sicherheitswerkbank angesaugt. Die dadurch bewirkte Luftströmung verhindert, dass eventuell kontaminierte Luft aus dem Innenraum in die Umgebung gelangt, und sorgt somit für einen Personenschutz. Zum Produktschutz, d.h. zum Schutz der im Innenraum befindlichen Arbeitsstoffe vor Kontamination durch Mikroorganismen oder andere Verunreinigungen in der zugeführten Umgebungsluft, wird die zugeführte Umgebungsluft vor dem Kontakt mit den Arbeitsstoffen zusammen mit einem Teil der Luft innerhalb der Sicherheitswerkbank mittels eines Gebläses umgewälzt und dabei mit Filtern gereinigt.Safety cabinets usually have a working opening on their front through which an operator sitting in front of the safety cabinet can insert their hands and forearms into a working area of the safety cabinet in which the working materials are located. A glass pane is arranged in front of the work opening, which offers the operator a good view of the working materials in the interior or work space. In order to protect operators and other persons in the vicinity of the safety workbench from the escape of working materials through the work opening, ambient air is sucked into the interior of the safety workbench through the work opening. The resulting air flow prevents any contaminated air from the interior from getting into the environment and thus ensures personal protection. For product protection, ie to protect the working materials inside from contamination by microorganisms or other impurities in the supplied ambient air, the supplied ambient air is circulated with a part of the air inside the safety workbench by means of a blower before it comes into contact with the working materials and is thereby cleaned with filters.

Aus der EP 1 312 871 B1 ist bereits eine Sicherheitswerkbank bekannt, bei der die Filter als Patronenfilter ausgebildet und mit mehreren nebeneinander angeordneten Filterpatronen der eingangs genannten Art bestückt sind. Diese Filterpatronen bestehen aus einem hohlzylindrischen Filterkörper, der einen Innenraum der Filterpatrone in radialer Richtung umgibt, einem mit einem oberen Ende des Filterkörpers vergossenen offenen Deckel, der eine in den Innenraum mündende Einströmöffnung umgibt, und einem mit einem unteren Ende des Filterkörpers vergossenen geschlossenen Deckel. Die durch die Arbeitsöffnung angesaugte Umgebungsluft und die in der Sicherheitswerkbank umgewälzte Luft strömen zuerst durch die Einströmöffnung in den Innenraum der Filterpatrone und treten von dort aus durch den Filterkörper bzw. das Filtermaterial hindurch, wobei die Luft gereinigt wird. Bei den Patronenfiltern handelt es sich um so genannte Mikro- oder HEPA-Filter.From the EP 1 312 871 B1 a safety workbench is already known, in which the filters are designed as cartridge filters and are equipped with a plurality of filter cartridges of the type mentioned at the beginning which are arranged next to one another. These filter cartridges consist of a hollow cylindrical filter body, which surrounds an interior of the filter cartridge in the radial direction, an open cover encapsulated with an upper end of the filter body, which surrounds an inflow opening opening into the interior, and a closed cover encapsulated with a lower end of the filter body. The ambient air sucked in through the working opening and the air circulated in the safety workbench first flow through the inflow opening into the interior of the filter cartridge and from there pass through the filter body or the filter material, the air being cleaned. The cartridge filters are so-called micro or HEPA filters.

Zwar hat sich gezeigt, dass diese Patronenfilter eine sehr gute Filterwirkung besitzen, jedoch wäre es von Vorteil, wenn ohne Beeinträchtigung der Filterwirkung und ohne eine Veränderung am Filterkörper bzw. am Filtermaterial der Volumenstrom durch die Filterpatrone vergrößert und/oder die Druckdifferenz zwischen der Einströmseite und der Ausströmseite verkleinert werden könnte. Dadurch könnte entweder bei gleicher Gebläseleistung mehr Luft durch die Filterpatrone umgewälzt werden, um die Strömungsmenge der durch die Arbeitsöffnung einströmenden Luft zu vergrößern und dadurch sowohl den Personenschutz und den Produktschutz zu verbessern, oder die Gebläseleistung ohne eine Veränderung der Strömungsverhältnisse reduziert und damit Energieeinsparungen erzielt werden.It has been shown that these cartridge filters have a very good filter effect, but it would be advantageous if the volume flow through the filter cartridge and / or the pressure difference between the inflow side and / or increased without impairing the filter effect and without changing the filter body or the filter material the outflow side could be reduced. As a result, more air could either be circulated through the filter cartridge with the same blower output in order to increase the flow rate of the air flowing in through the working opening and thereby improve both personal protection and product protection, or the blower output without one Changes in the flow conditions are reduced and energy savings are achieved.

Die GB 2 261 830 A offenbart bereits eine Filterpatrone gemäß dem Oberbegriff des Anspruchs 1. Der Vorsprung besitzt dort keine strömungstechnische Funktion, sondern ermöglich nur die Befestigung einer Zugstange. Die Anströmfläche des Vorsprungs umfasst an dessen Oberseite eine zur Längsmittelachse der Filterpatrone senkrechte ringförmige Oberfläche und eine von dieser umgebene vertiefte konische Oberfläche, die zusammen mindestens die Hälfte der Anströmfläche bilden. Dies führt bei hohen Strömungsgeschwindigkeiten zu erheblichen Turbulenzen und damit zu einer Abnahme der kinetischen Energie des Luftstroms, wodurch sich bei gleichem Druckgefälle über das Filtermaterial die durch das Filtermaterial strömende Luftmenge verringert. Außerdem nimmt die Strömungsgeschwindigkeit am oberen Ende des Vorsprungs wegen der Reduzierung des Strömungsquerschnitt abrupt zu, so dass sich dort weniger vom Luftstrom mitgeführte Partikel auf der Innenseite des Filterkörpers ablagern, was zu einer ungleichmäßigen Filterwirkung führt.The GB 2 261 830 A. already discloses a filter cartridge according to the preamble of claim 1. The projection there has no fluidic function, but only enables the attachment of a pull rod. The inflow surface of the projection comprises on its upper side an annular surface perpendicular to the longitudinal center axis of the filter cartridge and a recessed conical surface surrounded by it, which together form at least half of the inflow surface. At high flow velocities, this leads to considerable turbulence and thus to a decrease in the kinetic energy of the air flow, which reduces the amount of air flowing through the filter material at the same pressure drop across the filter material. In addition, the flow speed at the upper end of the projection increases abruptly because of the reduction in the flow cross section, so that fewer particles carried by the air flow are deposited on the inside of the filter body, which leads to an uneven filter effect.

Ausgehend hiervon liegt der Erfindung die Aufgabe zugrunde, eine Filterpatrone der eingangs genannten Art für einen Einsatz in einer Sicherheitswerkbank dahingehend zu verbessern, dass ohne eine Beeinträchtigung der Filterwirkung und ohne eine Veränderung am Filtermaterial der in Sicherheitswerkbänken verwendeten Filterpatronen die Strömungsmenge der durch den Filterkörper bzw. das Filtermaterial strömenden Luft vergrößert werden kann.Proceeding from this, the object of the invention is to improve a filter cartridge of the type mentioned at the outset for use in a safety workbench in such a way that without affecting the filter action and without changing the filter material of the filter cartridges used in safety workbenches, the flow rate of the through the filter body or the filter material flowing air can be enlarged.

Diese Aufgabe wird erfindungsgemäß durch die Merkmale des Anspruchs 1 gelöst. Bevorzugte Ausführungsformen sind in den abhängigen Ansprüchen definiert.This object is achieved by the features of claim 1. Preferred embodiments are defined in the dependent claims.

Die Anströmfläche an der Innenseite des nach innen über den geschlossenen Deckel überstehenden verjüngten Vorsprungs ist koaxial und rotationssymmetrisch zur Längsmittelachse der Filterpatrone und des Filterkörpers, um die Luft nach allen Seiten gleichmäßig umzulenken.The inflow surface on the inside of the tapered projection projecting inward beyond the closed cover is coaxial and rotationally symmetrical to the longitudinal center axis of the filter cartridge and the filter body in order to deflect the air evenly on all sides.

Bei Versuchen bzw. Messungen an einer Filterpatrone für eine Sicherheitswerkbank konnte festgestellt werden, dass sich die Strömungsmenge der durch den Filterkörper strömenden Luft ohne Veränderungen am Filtermaterial sowohl durch Veränderung der geometrischen Form der Einströmöffnung als auch durch Veränderung der geometrischen Form einer von der Luft angeströmten Fläche an der Innenseite des geschlossenen Deckels der Filterpatrone beeinflussen lässt. Weiter wurde bei den Versuchen bzw. Messungen festgestellt, dass sich durch Veränderung der geometrischen Form der Einströmöffnung auch die Druckdifferenz zwischen der Einströmseite und der Ausströmseite der Filterpatrone ohne Veränderungen am Filtermaterial beeinflussen lässt.In experiments or measurements on a filter cartridge for a safety workbench, it was found that the flow rate of the air flowing through the filter body changes without changes to the filter material both by changing the geometric shape of the inflow opening and by changing the geometric shape of a surface against which the air flows on the inside of the closed lid of the filter cartridge. It was also found during the tests and measurements that by changing the geometric shape of the inflow opening, the pressure difference between the inflow side and the outflow side of the filter cartridge can be influenced without changes to the filter material.

Eine Reduzierung der Druckdifferenz zwischen der Einströmseite und der Ausströmseite der Filterpatrone wird vor allem dann erreicht, wenn die Einströmöffnung erfindungsgemäß einen in Richtung des Innenraums abnehmenden düsenartigen Strömungsquerschnitt aufweist, während eine Vergrößerung der Strömungsmenge, d.h. der pro Zeiteinheit durch den Filterkörper strömenden Luftmenge, durch die erfindungsgemäße Abnahme des Strömungsquerschnitts der Einströmöffnung in Richtung des Innenraums und durch den gemäß der Erfindung am geschlossenen Deckel zur Einströmöffnung hin in den Innenraum überstehenden verjüngten Vorsprung erreicht werden kann.A reduction in the pressure difference between the inflow side and the outflow side of the filter cartridge is achieved above all if the inflow opening has, according to the invention, a nozzle-like flow cross section which decreases in the direction of the interior, while an increase in the flow rate, i.e. the amount of air flowing through the filter body per unit of time, through the decrease in the flow cross-section of the inflow opening in the direction of the interior according to the invention and through the tapered projection which projects according to the invention on the closed cover towards the inflow opening into the interior.

Bei den Versuchen wurde weiter festgestellt, dass bei einer Filterpatrone mit einer erfindungsgemäßen Einströmöffnung deutlich weniger Turbulenzen im Innenraum der Filterpatrone auftreten und dass die Turbulenzen nahezu völlig verschwinden, wenn der geschlossene Deckel durch den überstehenden verjüngten Vorsprung statt mit einer zur Einströmrichtung senkrechten Anströmfläche mit einer zur Strömungsrichtung der einströmenden Luft schräg geneigten Anströmfläche versehen wird, die dafür sorgt, dass die Luft mit weniger Turbulenzen in Richtung der Innenseite der hohlzylindrischen Filterkörpers umgelenkt wird.During the tests it was also found that in a filter cartridge with an inflow opening according to the invention Significantly less turbulence occurs in the interior of the filter cartridge and that the turbulence almost completely disappears if the closed cover is provided with an inflow surface that is inclined to the direction of flow of the inflow, instead of having an inflow surface that is perpendicular to the inflow direction, which ensures that the air is deflected towards the inside of the hollow cylindrical filter body with less turbulence.

Der offene Deckel ist vorzugsweise so ausgebildet, dass der Strömungsquerschnitt der Einströmöffnung bereits außerhalb des Filterkörpers bzw. in Strömungsrichtung der Luft vor dem Erreichen des Filterkörpers abnimmt, so dass die gesamte Länge des Filterkörpers zur Luftfilterung ausgenutzt werden kann, ohne dass die Luft innerhalb des Filterkörpers bzw. hinter der Einströmöffnung wieder entgegen der Einströmrichtung umgelenkt werden muss.The open cover is preferably designed such that the flow cross-section of the inflow opening already decreases outside the filter body or in the direction of flow of the air before reaching the filter body, so that the entire length of the filter body can be used for air filtering without the air inside the filter body or must be redirected behind the inflow opening against the inflow direction.

Gemäß einer vorteilhaften Ausgestaltung der Erfindung ist das Verhältnis zwischen dem kleinsten Strömungsquerschnitt an einem inneren Ende der Einströmöffnung und dem größten Strömungsquerschnitt an einem äußeren Ende der Einströmöffnung kleiner als 0,75 und vorzugsweise kleiner als 0,5, so dass die Luft innerhalb der Einströmöffnung wie in einer Düse beschleunigt wird. Es wird angenommen, dass diese Beschleunigung eine der Ursachen für die Vergrößerung des Volumenstroms durch die Filterpatrone ist. Die Reduzierung des Strömungsquerschnitts erfolgt vorteilhaft über eine relativ kurze Strecke, deren Länge zweckmäßig weniger als ein Zehntel der Länge der Filterpatrone beträgt, so dass die düsenartige Einströmöffnung innerhalb des Gehäuses der Sicherheitswerkbank wenig Platz benötigt.According to an advantageous embodiment of the invention, the ratio between the smallest flow cross section at an inner end of the inflow opening and the largest flow cross section at an outer end of the inflow opening is less than 0.75 and preferably less than 0.5, so that the air inside the inflow opening is like is accelerated in a nozzle. It is believed that this acceleration is one of the causes of the increase in volume flow through the filter cartridge. The flow cross-section is advantageously reduced over a relatively short distance, the length of which is expediently less than one tenth of the length of the filter cartridge, so that the nozzle-like inflow opening requires little space within the housing of the safety workbench.

Eine weitere zweckmäßige Ausgestaltung der Erfindung sieht vor, dass die Einströmöffnung an ihrem inneren Ende von einem zur Längsmittelachse der Filterpatrone koaxialen hohlzylindrischen kurzen Steg begrenzt wird, der ein wenig ins Innere des Filterkörpers ragt und eine zum Filterkörper hin offene flache Nut begrenzt, in der das benachbarte Stirnende des Filterkörpers vergossen werden kann. Um das Vergießen des benachbarten Stirnendes des Filterkörpers zu ermöglichen, wird die Nut auch nach außen zu von einem zur Längsmittelachse der Filterpatrone koaxialen Steg begrenzt, der die äußere Umfangsfläche des Filterkörpers an dessen benachbartem Stirnende umgibt.A further expedient embodiment of the invention provides that the inflow opening at its inner end is delimited by a hollow cylindrical short web coaxial with the longitudinal central axis of the filter cartridge, which protrudes a little into the interior of the filter body and delimits a flat groove which is open towards the filter body and in which the adjacent front end of the filter body can be shed. In order to enable the adjacent end face of the filter body to be cast, the groove is also delimited on the outside by a web which is coaxial with the longitudinal center axis of the filter cartridge and which surrounds the outer peripheral surface of the filter body at its adjacent end face.

Zur Montage der Filterpatrone in der Sicherheitswerkbank weist der offene Deckel der Filterpatrone vorteilhaft einen in radialer Richtung der Längsmittelachse über den äußeren Umfang des Filterkörpers überstehenden Randflansch auf. Über die vom Filterkörper abgewandte Seite des Randflanschs steht zweckmäßig ein ringförmiger Vorsprung über, der die Einströmöffnung außerhalb der Filterpatrone umgibt und in radialer Richtung begrenzt. Der Randflansch und der zur Materialeinsparung zweckmäßig hohle ringförmige Vorsprung sind vorteilhaft aus thermoplastischem Kunststoff ausgebildet, um dadurch der Einströmöffnung auf einfache Weise eine gewünschte Kontur zu verleihen. Der offene Deckel kann einstückig oder mehrteilig ausgeführt sein, wobei im zuerst genannten Fall der Randflansch und der Vorsprung bevorzugt integrale Teile des offenen Deckels sind.To mount the filter cartridge in the safety workbench, the open cover of the filter cartridge advantageously has an edge flange which projects beyond the outer circumference of the filter body in the radial direction of the longitudinal center axis. An annular projection, which surrounds the inflow opening outside the filter cartridge and delimits it in the radial direction, expediently projects over the side of the edge flange facing away from the filter body. The edge flange and the hollow annular projection, which is expedient to save material, are advantageously made of thermoplastic plastic, in order thereby to give the inflow opening a desired contour in a simple manner. The open cover can be made in one piece or in several parts, the edge flange and the projection preferably being integral parts of the open cover in the first-mentioned case.

Vorzugsweise weist die Einströmöffnung eine zu einer Längsmittelachse der Filterpatrone und des Filterkörpers koaxiale rotationssymmetrische Begrenzungsfläche auf, deren Neigungswinkel in Strömungsrichtung der Luft durch die Einströmöffnung zunimmt.The inflow opening preferably has a rotationally symmetrical boundary surface which is coaxial with a longitudinal center axis of the filter cartridge and the filter body and whose angle of inclination increases in the direction of flow of air through the inflow opening.

Vorteilhafterweise ist der Außendurchmesser der Anströmfläche an einem von der Einströmöffnung abgewandten Fuß des Vorsprungs etwas kleiner als der Innendurchmesser des Filterkörpers, so dass ein Teil der Luft am Vorsprung vorbei bis ganz zum Ende des Filterkörpers strömen und so der Filterkörper über seine gesamte Länge zur Luftfilterung ausgenutzt werden kann.Advantageously, the outside diameter of the inflow surface on a foot of the projection facing away from the inflow opening is somewhat smaller than the inside diameter of the filter body, so that part of the air flows past the projection to the very end of the filter body and the filter body is thus used over its entire length for air filtering can be.

Vorteilhaft sind auch der geschlossene Deckel und der Vorsprung einstückig aus thermoplastischem Kunststoff ausgebildet, wobei der Vorsprung an der Außenseite des geschlossenen Deckels zweckmäßig eine Vertiefung mit einer der Form des Vorsprungs entsprechenden Form begrenzt, so dass der geschlossene Deckel über seinen gesamten Durchmesser möglichst dünnwandig und damit materialsparend ausgebildet werden kann.The closed cover and the projection are also advantageously formed in one piece from thermoplastic material, the projection on the outside of the closed cover expediently delimiting a depression with a shape corresponding to the shape of the projection, so that the closed cover is as thin-walled as possible over its entire diameter and thus can be trained to save material.

Darüber hinaus hat sich bei den Versuchen und Messungen gezeigt, dass im Hinblick auf eine Erhöhung des Luftdurchsatzes bzw. der Strömungsmenge mit relativ niedrigen Vorsprüngen bessere Ergebnisse erzielt werden können, z.B. wenn die Höhe des Vorsprungs weniger als ein Viertel und vorzugsweise weniger als ein Fünftel der axialen Länge des Filterkörpers beträgt.In addition, it has been shown in the tests and measurements that, with regard to increasing the air throughput or the flow rate, better results can be achieved with relatively low projections, e.g. if the height of the projection is less than a quarter and preferably less than a fifth of the axial length of the filter body.

Um zu vermeiden, dass das zickzackförmig gefaltete und zu einem Hohlzylinder geformte, aus Papier bestehende Filtermaterial bei der Handhabung der Filterpatrone beschädigt werden kann, kann der Filterkörper zwischen dem offenen und dem geschlossenen Deckel zweckmäßig von einem luftdurchlässigen Griffschutz umgeben sein, der bei der Handhabung einen Kontakt mit dem Filterkörper verhindert.In order to avoid that the zigzag folded and shaped into a hollow cylinder, made of paper filter material can be damaged when handling the filter cartridge, the filter body between the open and the closed lid can be surrounded by an air-permeable handle protection, which during handling Prevents contact with the filter body.

Im Folgenden wird die Erfindung anhand eines in der Zeichnung dargestellten Ausführungsbeispiels näher erläutert.

  • Fig. 1 zeigt eine schematische, teilweise geschnittene Seitenansicht einer erfindungsgemäßen Sicherheitswerkbank;
  • Fig. 2 zeigt eine perspektivische Ansicht eines Filtergehäuses der Sicherheitswerkbank mit sechs Filterpatronen;
  • Fig. 3 zeigt eine vergrößerte Schnittansicht entlang der Linie III - III der Fig. 2;
  • Fig. 4 zeigt eine vergrößerte perspektivische Ansicht einer erfindungsgemäßen Filterpatrone;
  • Fig. 5 zeigt eine Oberseitenansicht der Filterpatrone;
  • Fig. 6 zeigt eine auseinander gezogene perspektivische Ansicht der Teile der Filterpatrone;
  • Fig. 7 zeigt eine Längsschnittansicht der Filterpatrone entlang der Linie VII-VII der Fig. 5;
  • Fig. 8 zeigt eine entsprechende Längsschnittansicht einer anderen erfindungsgemäßen Filterpatrone;
  • Fig. 9 zeigt eine entsprechende Längsschnittansicht einer weiteren erfindungsgemäßen Filterpatrone;
  • Fig. 10 zeigt eine entsprechende Längsschnittansicht einer nicht zur Erfindung gehörenden Ausführung einer Filterpatrone;
  • Fig. 11 zeigt eine auseinander gezogene perspektivische Ansicht der Teile einer noch weiteren erfindungsgemäßen Filterpatrone.
The invention is explained in more detail below on the basis of an exemplary embodiment shown in the drawing.
  • Fig. 1 shows a schematic, partially sectioned side view of a safety workbench according to the invention;
  • Fig. 2 shows a perspective view of a filter housing of the safety cabinet with six filter cartridges;
  • Fig. 3 shows an enlarged sectional view along the line III - III of Fig. 2 ;
  • Fig. 4 shows an enlarged perspective view of a filter cartridge according to the invention;
  • Fig. 5 shows a top view of the filter cartridge;
  • Fig. 6 shows an exploded perspective view of the parts of the filter cartridge;
  • Fig. 7 shows a longitudinal sectional view of the filter cartridge along the line VII-VII of Fig. 5 ;
  • Fig. 8 shows a corresponding longitudinal sectional view of another filter cartridge according to the invention;
  • Fig. 9 shows a corresponding longitudinal sectional view of a further filter cartridge according to the invention;
  • Fig. 10 shows a corresponding longitudinal sectional view of an embodiment of the filter cartridge not belonging to the invention;
  • Fig. 11 shows an exploded perspective view of the parts of yet another filter cartridge according to the invention.

Die in der Zeichnung dargestellte, zum Umgang mit cancerogenen, mutagenen oder fruchtbarkeitsgefährdenden bzw. pathogenen Arbeitsstoffen bestimmte Sicherheitswerkbank 10 besteht im Wesentlichen aus einem höhenverstellbaren Unterteil oder Untergestell 12 und einem Oberteil 14 mit einem Gehäuse 16, das einen zur Handhabung der Arbeitsstoffe dienenden Arbeitsraum 18 umgibt.The safety workbench 10 shown in the drawing and intended for handling carcinogenic, mutagenic or fertility-endangering or pathogenic working substances essentially consists of a height-adjustable lower part or base frame 12 and an upper part 14 with a housing 16 which surrounds a working space 18 serving for handling the working substances .

Wie am besten in Fig. 1 und 2 dargestellt, wird der Arbeitsraum 18 an einer Frontseite der Sicherheitswerkbank 10 von einer Glasscheibe 20 begrenzt, die einer vor der Sicherheitswerkbank 10 sitzenden Bedienungsperson (nicht dargestellt) eine gute Sicht in den Arbeitsraum 18 gewährt. Unterhalb von der Glasscheibe 20 befindet sich eine langgestreckte schlitzartige Arbeitsöffnung 22, durch welche die Bedienungsperson zum Umgang mit den Arbeitsstoffen ihre Unterarme und Hände in den Arbeitsraum 18 einführen kann.As best in Fig. 1 and 2nd shown, the work area 18 is delimited on a front side of the safety workbench 10 by a glass pane 20 which allows an operator (not shown) sitting in front of the safety workbench 10 to have a good view of the work space 18. Below the glass pane 20 is an elongated slot-like working opening 22 through which the operator can handle it can introduce their forearms and hands into the work area 18 with the working materials.

Das Oberteil 14 des Gehäuses 16 enthält unter anderem ein Gebläse 24, zwei oberhalb des Arbeitsraums 18 angeordnete HEPA-Filter 26 und 28, sowie sechs unterhalb des Arbeitsraums 18 angeordnete HEPA-Filter 30.The upper part 14 of the housing 16 contains, among other things, a blower 24, two HEPA filters 26 and 28 arranged above the working space 18, and six HEPA filters 30 arranged below the working space 18.

Um zu verhindern, dass die im Arbeitsraum 18 befindlichen Arbeitsstoffe durch die Arbeitsöffnung 22 in die Umgebung austreten, ist an der Unterseite des Arbeitsraums 18 unmittelbar hinter der Arbeitsöffnung 22 eine rinnenförmige Absaugöffnung 32 angeordnet, die sich ebenso wie die Glasscheibe 20 und die Arbeitsöffnung 22 im Wesentlichen über die gesamte Breite der Sicherheitswerkbank 10 erstreckt. Die Absaugöffnung 32 ist ebenso wie weitere, am Boden des Arbeitsraums 18 angeordnete Absaugöffnungen (nicht dargestellt) durch ein Plenum 34 mit der Einlass- oder Rohluftseite 36 der HEPA-Filter 30 verbunden, deren Auslass- oder Reinluftseite 38 durch einen Saugkanal 40 an der Rückseite des Gehäuses 16 mit der Saugseite des Gebläses 24 verbunden ist. Das Gebläse 24 erzeugt durch die Filter 30 einen leichten Unterdruck im Plenum 34, wodurch aus der Umgebung und aus dem Arbeitsraum 18 Luft durch die Arbeitsöffnung 22 in die rinnenförmige Absaugöffnung 32 angesaugt wird, wie durch die Pfeile A in Fig. 1 dargestellt.In order to prevent the working materials located in the working space 18 from escaping into the environment through the working opening 22, a channel-shaped suction opening 32 is arranged on the underside of the working space 18 immediately behind the working opening 22, which, like the glass pane 20 and the working opening 22, are arranged in the Extends essentially over the entire width of the safety workbench 10. The suction opening 32, as well as further suction openings (not shown) arranged at the bottom of the work space 18, are connected by a plenum 34 to the inlet or unfiltered air side 36 of the HEPA filter 30, the outlet or clean air side 38 thereof by a suction channel 40 on the rear side of the housing 16 is connected to the suction side of the fan 24. The fan 24 generates a slight negative pressure in the plenum 34 through the filters 30, as a result of which air is drawn in from the surroundings and from the working space 18 through the working opening 22 into the channel-shaped suction opening 32, as indicated by the arrows A in Fig. 1 shown.

Die angesaugte Luft strömt anschließend durch die Filter 30 und den Saugkanal 40 zum Gebläse 24. Von dort wird ein Teil der Luft durch den HEPA-Filter 26 von oben her in den Arbeitsraum 18 geblasen, wo die Luft entlang der Glasscheibe 20 nach unten strömt, wie durch die Pfeile B in Fig. 1 dargestellt. Ein anderer Teil der Luft wird durch eine oberhalb vom Gebläse 24 und vom HEPA-Filter 28 an der Oberseite des Oberteils 14 angeordneten Abluftanschluss 39 aus dem Oberteil 14 der Sicherheitswerkbank 10 abgeführt, wie durch die Pfeile C in Fig. 1 dargestellt.The sucked-in air then flows through the filters 30 and the suction channel 40 to the blower 24. From there, part of the air is blown through the HEPA filter 26 from above into the working space 18, where the air flows down along the glass pane 20, as by arrows B in Fig. 1 shown. Another part of the air is through one above the fan 24 and the HEPA filter 28 on the top of the upper part 14 arranged exhaust air connection 39 discharged from the upper part 14 of the safety workbench 10, as indicated by the arrows C in Fig. 1 shown.

Wie am besten in Fig. 2 und 3 dargestellt, handelt es sich bei den HEPA-Filtern 30 um Patronenfilter, die nebeneinander in einem im Querschnitt keilförmigen Filtergehäuse 44 angeordnet sind, das sich über die gesamte Breite der Sicherheitswerkbank 10 erstreckt. Das Filtergehäuse 44 wird zum Plenum 34 hin von einer schrägen Zwischenwand 42 mit sechs kreisförmigen Öffnungen begrenzt. In jede der Öffnungen ist von oben her eine austauschbare Filterpatrone 46 eingesetzt, die schräg nach unten in einen mit dem Saugkanal 40 kommunizierenden Innenraum des Filtergehäuse 40 ragt.As best in 2 and 3 As shown, the HEPA filters 30 are cartridge filters which are arranged next to one another in a filter housing 44 which is wedge-shaped in cross section and extends over the entire width of the safety workbench 10. The filter housing 44 is delimited towards the plenum 34 by an inclined intermediate wall 42 with six circular openings. An exchangeable filter cartridge 46 is inserted into each of the openings from above, which protrudes obliquely downward into an interior of the filter housing 40 that communicates with the suction channel 40.

Wie am besten in Fig. 6 dargestellt, besteht jede Filterpatrone 46 aus einem hohlzylindrischen Filterkörper 48, einem am oberen Ende des Filterkörpers 48 befestigten offenen Deckel 50, einem zwischen dem Filterkörper 48 und dem Deckel 50 angeordneten ebenen Dichtungselement 52 und einem am unteren Ende des Filterkörpers 48 befestigten geschlossenen Deckel 54.As best in Fig. 6 each filter cartridge 46 consists of a hollow cylindrical filter body 48, an open cover 50 attached to the upper end of the filter body 48, a flat sealing element 52 arranged between the filter body 48 and the cover 50, and a closed cover 54 attached to the lower end of the filter body 48.

Der Filterkörper 48 besteht aus einem zickzackförmig gefalteten Filtermaterial, das zu einem Hohlzylinder geformt ist und einen zylindrischen Innenraum 56 umgibt. Die zur Faltung parallelen Enden des Filtermaterials sind entlang einer Längsklebenaht dicht miteinander verbunden. Die entgegengesetzten Stirnenden des Filterkörpers 48 sind luftdicht mit dem offenen Deckel 50 und dem Dichtungselement 52 einerseits bzw. dem geschlossenen Deckel 54 andererseits vergossen.The filter body 48 consists of a zigzag folded filter material which is shaped into a hollow cylinder and surrounds a cylindrical interior 56. The ends of the filter material that are parallel to the pleating are tightly connected to one another along a longitudinal adhesive seam. The opposite ends of the filter body 48 are sealed airtight with the open cover 50 and the sealing element 52 on the one hand and the closed cover 54 on the other hand.

Der aus einem thermoplastischen Kunststoff bestehende offene Deckel 50 ist einstückig ausgebildet und ist an seiner dem Filterkörper 48 zugewandten Seite mit einem integrierten Randflansch 60 versehen. Der ebene, zu einer Längsmittelachse 66 der Filterpatrone 46 und des Filterkörpers 48 senkrechte Randflansch 60 besitzt einen quadratischen äußeren Umriss. Über die vom Filterkörper 48 abgewandte Oberseite des Randflanschs 60 steht ein hohler ringförmiger Vorsprung 64 über, der eine zur Längsmittelachse 66 koaxiale Einströmöffnung 70 umgibt. Durch die Einströmöffnung 70 strömt nach der Montage der Filterpatrone 46 im Betrieb der Sicherheitswerkbank 10 die Rohluft aus dem Plenum 34 in den Innenraum 56 des Filterkörpers 48.The open cover 50, which is made of a thermoplastic material, is formed in one piece and has an integrated one on its side facing the filter body 48 Edge flange 60 provided. The flat edge flange 60, which is perpendicular to a longitudinal center axis 66 of the filter cartridge 46 and the filter body 48, has a square outer contour. A hollow annular projection 64, which surrounds an inflow opening 70 coaxial with the longitudinal center axis 66, projects beyond the upper side of the edge flange 60 facing away from the filter body 48. After the installation of the filter cartridge 46 during the operation of the safety workbench 10, the raw air flows from the plenum 34 into the interior 56 of the filter body 48 through the inflow opening 70.

Die Einströmöffnung 70 weist eine zur Längsmittelachse 66 koaxiale rotationssymmetrische Begrenzungsfläche auf. Die Begrenzungsfläche besteht aus drei in Strömungsrichtung hintereinander angeordneten Teilflächen. Die erste Teilfläche ist unter einem Winkel von etwa 30 Grad und die zweite Teilfläche unter einem Winkel von etwa 45 Grad zu einer zum Randflansch 60 parallelen Ebene geneigt, so dass der Neigungswinkel der Teilflächen in Strömungsrichtung der Luft durch die Einströmöffnung 70 zunimmt.The inflow opening 70 has a rotationally symmetrical boundary surface coaxial with the longitudinal central axis 66. The boundary surface consists of three partial surfaces arranged one behind the other in the direction of flow. The first partial surface is inclined at an angle of approximately 30 degrees and the second partial surface is inclined at an angle of approximately 45 degrees to a plane parallel to the edge flange 60, so that the angle of inclination of the partial surfaces increases in the direction of flow of air through the inflow opening 70.

Wie am besten in Fig. 2, 3 und 4 dargestellt, liegen der Randflansch 60 bzw. das unter dem Randflansch 60 angeordnete ebene Dichtungselement 52 nach der Montage der Filterpatrone 46 von oben her gegen die ebene Zwischenwand 42 an. Zur Befestigung und Abdichtung der Filterpatrone 46 wird der Randflansch 60 mit vier das Dichtungselement 52 durchsetzenden Schrauben (nicht dargestellt) von oben an der Zwischenwand 24 festgeschraubt. Zu diesem Zweck weist das Dichtungselement 52 in seinen vier Ecken jeweils eine Durchtrittsöffnung 80 für eine der Befestigungsschrauben des Randflanschs 60 auf.As best in 2, 3 and 4th As shown, the edge flange 60 or the flat sealing element 52 arranged under the edge flange 60 abuts against the flat intermediate wall 42 from above after the filter cartridge 46 has been installed. To secure and seal the filter cartridge 46, the edge flange 60 is screwed onto the intermediate wall 24 from above with four screws (not shown) passing through the sealing element 52. For this purpose, the sealing element 52 has in each of its four corners a passage opening 80 for one of the fastening screws of the edge flange 60.

Wie am besten in Fig. 4, 6 und 7 dargestellt, besitzt die vom Vorsprung 64 begrenzte Einströmöffnung 70 einen zum Innenraum 56 hin abnehmenden Strömungsquerschnitt, so dass die Rohluft beim Eintritt in die Filterpatrone 46 beschleunigt wird, während sie die Einströmöffnung 70 passiert. Die Höhe des Vorsprungs 64 und damit die Länge der verjüngten düsenartigen Einströmöffnung 70 beträgt weniger als ein Zehntel der Länge der Filterpatrone 46 und ist damit relativ klein. Der Strömungsquerschnitt am oberen oder äußeren Ende der verjüngten Einströmöffnung 70 ist mehr als doppelt so groß wie der kleinste Strömungsquerschnitt am unteren oder inneren Ende der Einströmöffnung 70, so dass die einströmende Luft über eine kurze Distanz stark beschleunigt wird.As best in Fig. 4 , 6 and 7 shown, the inflow opening 70 delimited by the projection 64 has an interior 56 decreasing flow cross-section, so that the unfiltered air is accelerated when it enters the filter cartridge 46 as it passes through the inflow opening 70. The height of the projection 64 and thus the length of the tapered nozzle-like inflow opening 70 is less than a tenth of the length of the filter cartridge 46 and is therefore relatively small. The flow cross-section at the upper or outer end of the tapered inflow opening 70 is more than twice the smallest flow cross-section at the lower or inner end of the inflow opening 70, so that the inflowing air is greatly accelerated over a short distance.

Das untere oder innere Ende der Einströmöffnung 70 wird von einem kurzen ringförmigen hohlzylindrischen Steg 72 begrenzt, der die dritte Teilfläche bildet. Der Steg 72 ragt ein wenig in den Innenraum 56 des Filterkörpers 48 und bildet die innere Begrenzung einer flachen Nut 74 auf der dem Filterkörper 48 zugewandten Seite des offenen Deckels 50 bzw. des Filterelements 52, in der das obere Stirnende des Filterkörpers 48 vergossen wird. Die obere Begrenzung 76 der Nut 74 wird vom Dichtungselement 52 gebildet, während die äußere Begrenzung der Nut 74 von einem über die Unterseite des Dichtungselements 52 überstehenden kurzen ringförmigen Steg 62 (Fig. 7) gebildet wird.The lower or inner end of the inflow opening 70 is delimited by a short annular hollow cylindrical web 72, which forms the third partial surface. The web 72 protrudes a little into the interior 56 of the filter body 48 and forms the inner boundary of a flat groove 74 on the side of the open cover 50 or the filter element 52 facing the filter body 48, in which the upper front end of the filter body 48 is cast. The upper boundary 76 of the groove 74 is formed by the sealing element 52, while the outer boundary of the groove 74 is formed by a short annular web 62 () projecting beyond the underside of the sealing element 52 Fig. 7 ) is formed.

Alternativ können der Deckel 50 und das Dichtungselement 52 einstückig als integrales Bauteil hergestellt werden, wobei dann die Nut 74 nach oben zu von einem geschlossenen Boden des hohlen Vorsprungs 64 begrenzt wird, während ihre innere und äußere Begrenzung von kurzen ringförmigen Stegen gebildet wird, die nach unten über den geschlossenen Boden des hohlen Vorsprungs 64 überstehen.Alternatively, the cover 50 and the sealing element 52 can be produced in one piece as an integral component, in which case the groove 74 is delimited upwards by a closed bottom of the hollow projection 64, while its inner and outer delimitation is formed by short annular webs which follow project below the closed bottom of the hollow projection 64.

An der Unterseite des Dichtungselements 52 befindet sich eine aus einem Schaumstoffmaterial bestehende ebene Dichtung (nicht dargestellt), die wie der Randflansch 60 einen quadratischen äußeren Umriss und eine kreisförmige innere Durchtrittsöffnung aufweist, deren Innendurchmesser etwas größer ist als der Außendurchmesser des Filterkörpers 48.On the underside of the sealing element 52 there is a flat seal (not shown) consisting of a foam material, which like the edge flange 60 has a square outer contour and a circular inner passage opening, the inside diameter of which is somewhat larger than the outside diameter of the filter body 48.

Der geschlossene Deckel 54 am unteren Ende des Filterkörpers 48 besteht ebenfalls aus einem thermoplastischen Kunststoff. Wie am besten in Fig. 6 dargestellt, umfasst der einstückig ausgebildete Deckel 54 einen zum Filterkörper 48 hin überstehenden hohlzylindrischen äußeren Umfangsrand 82 mit einem dem Außendurchmesser des Filterkörpers 48 entsprechenden Innendurchmesser, einen nach innen an den Umfangsrand 82 angrenzenden ringförmigen ebenen Bodenteil 84, der eine Anlagefläche für das mit dem Deckel 54 vergossene untere Stirnende des Filterkörpers 48 bildet, sowie einen mittigen, in Richtung der Einströmöffnung 70 verjüngten kegelförmigen Vorsprung 86, der ein Stück weit in den Innenraum 56 des Filterkörpers 48 ragt.The closed cover 54 at the lower end of the filter body 48 also consists of a thermoplastic. As best in Fig. 6 As shown, the one-piece cover 54 includes a hollow cylindrical outer peripheral edge 82 protruding towards the filter body 48 with an inner diameter corresponding to the outer diameter of the filter body 48, an annular flat bottom part 84 adjoining the peripheral edge 82 and providing a contact surface for the cover 54 encapsulated lower end of the filter body 48 forms, as well as a central, conical projection 86 tapering in the direction of the inflow opening 70, which protrudes a little into the interior 56 of the filter body 48.

Der kegelförmige Vorsprung 86 weist an seiner Innenseite eine der Einströmöffnung 70 zugewandte Anströmfläche 90 auf, die unter einem Winkel von etwa 45 Grad gegenüber dem ringförmigen ebenen Bodenteil 84 und auch in Bezug zur Längsmittelachse 66 geneigt und symmetrisch zur Längsmittelachse 66 ist. Der Durchmesser am Fuß des kegelförmigen Vorsprungs 86 ist etwas kleiner als der Innendurchmesser des Filterkörpers 48, so dass ein Teil der einströmenden Luft am Vorsprung 86 entlang bis zum unteren Ende des Filterkörpers 48 gelangen kann. Die Spitze des kegelförmigen Vorsprungs 86 kann leicht gerundet sein, wie in Fig. 7 dargestellt. Die Höhe des Vorsprungs 86 beträgt etwa ein Sechstel bis ein Siebentel der Länge des Filterkörpers 48.On its inside, the conical projection 86 has an inflow surface 90 facing the inflow opening 70, which is inclined at an angle of approximately 45 degrees with respect to the annular flat base part 84 and also with respect to the longitudinal central axis 66 and is symmetrical to the longitudinal central axis 66. The diameter at the foot of the conical projection 86 is somewhat smaller than the inside diameter of the filter body 48, so that part of the inflowing air can pass along the projection 86 to the lower end of the filter body 48. The tip of the conical projection 86 can be slightly rounded, as in FIG Fig. 7 shown. The height of the projection 86 is approximately one sixth to one seventh the length of the filter body 48.

Die Wanddicke des geschlossenen Deckels 54 ist über dessen gesamten Durchmesser gleich, so dass der geschlossene Deckel 54 an der Außen- oder Unterseite der Filterpatrone 46 eine dem Vorsprung 86 entsprechende kegelförmige Vertiefung (nicht sichtbar) besitzt.The wall thickness of the closed cover 54 is the same over its entire diameter, so that the closed cover 54 on the outside or underside of the filter cartridge 46 has a conical depression corresponding to the projection 86 (not visible).

Im Unterschied zu der Filterpatrone 46 in den Figuren 4 bis 7 besitzt bei der Filterpatrone 46 in Fig. 8 der in den Innenraum 56 überstehende Vorsprung 92 die Form einer Halbkugel, deren Pol der Einströmöffnung 70 zugewandt ist und deren Äquator an den ringförmigen ebenen Bodenteil 84 angrenzt. Die Höhe des Vorsprungs 92 und der Durchmesser an dessen Fuß entsprechen denjenigen des Vorsprungs 86 aus den Figuren 6 und 7.In contrast to the filter cartridge 46 in the Figures 4 to 7 has 46 in Fig. 8 the protrusion 92 protruding into the interior 56 has the shape of a hemisphere, the pole of which faces the inflow opening 70 and the equator of which adjoins the annular, flat bottom part 84. The height of the projection 92 and the diameter at its base correspond to that of the projection 86 from FIGS Figures 6 and 7 .

Bei der Filterpatrone in Fig. 9 ist der Vorsprung 94 wie bei der Filterpatrone 46 in Fig. 7 kegelförmig, ragt jedoch erheblich weiter in den Innenraum 56, wobei seine Höhe etwa sieben Zehntel der Länge des Filterkörpers 48 entspricht. Die Neigung der Anströmfläche 90 an der Innenseite des Vorsprungs 94 ist daher steiler als bei der Filterpatrone 46 in Fig. 7, wobei der Neigungswinkel gegenüber dem ringförmigen ebenen Bodenteil 84 etwa 80 Grad beträgt. Die Spitze des Vorsprungs 94 ist leicht konvex gerundet.With the filter cartridge in Fig. 9 the protrusion 94 is like in the filter cartridge 46 in Fig. 7 conical, but protrudes considerably further into the interior 56, its height corresponding to about seven tenths of the length of the filter body 48. The inclination of the inflow surface 90 on the inside of the projection 94 is therefore steeper than in the case of the filter cartridge 46 in FIG Fig. 7 , wherein the angle of inclination with respect to the annular flat bottom part 84 is approximately 80 degrees. The tip of the projection 94 is rounded slightly convex.

Bei der Filterpatrone 46 in Fig. 10 weist der geschlossene Deckel 54 keinen nach innen überstehenden Vorsprung auf, sondern ist eben und senkrecht zur Längsmittelachse 66 der Filterpatrone 46 ausgerichtet.With the filter cartridge 46 in Fig. 10 the closed cover 54 does not have an inwardly projecting projection, but is aligned flat and perpendicular to the longitudinal central axis 66 of the filter cartridge 46.

Bei den Filterpatronen 46 in den Figuren 8 bis 10 weist der offene Deckel 50 jeweils dieselbe düsenartige Einströmöffnung 70 wie bei der Filterpatrone 46 in den Figuren 4 bis 7 auf.In the filter cartridges 46 in the Figures 8 to 10 the open cover 50 each has the same nozzle-like inflow opening 70 as in the filter cartridge 46 in FIGS Figures 4 to 7 on.

Bei Strömungs- und Druckmessungen an den in der Zeichnung dargestellten Filterpatronen 46 konnte im Vergleich zu einer Filterpatrone mit einem flachen offenen Deckel und einem ebenen zur Längsmittelachse senkrechten geschlossenen Deckel gemäß der EP 1 312 871 B1 die Strömungsmenge der durch den Filterkörper 48 strömenden Luft ohne Veränderungen am Filtermaterial bei den Filterpatronen 46 in Fig. 7 und 8 jeweils um etwa 15 % und bei den Filterpatronen 46 in Fig. 9 und 10 jeweils um etwa 5 bis 6 % vergrößert werden.During flow and pressure measurements on the filter cartridges 46 shown in the drawing, in comparison with a filter cartridge with a flat open cover and a flat closed cover perpendicular to the longitudinal central axis, according to FIG EP 1 312 871 B1 the flow rate of the air flowing through the filter body 48 without changes to the filter material in the filter cartridges 46 in 7 and 8 each by about 15% and for the filter cartridges 46 in 9 and 10 each be enlarged by about 5 to 6%.

Bei Strömungs- und Druckmessungen an den beiden in Fig. 9 und 10 dargestellten Filterpatronen 46 konnte im Vergleich zu einer Filterpatrone gemäß der EP 1 312 871 B1 die Druckdifferenz zwischen der Einströmseite 36 und der Ausströmseite 38 ohne Veränderungen am Filtermaterial jeweils um etwa 5 % verkleinert werden.For flow and pressure measurements on the two in 9 and 10 filter cartridges 46 could be compared to a filter cartridge according to the EP 1 312 871 B1 the pressure difference between the inflow side 36 and the outflow side 38 can each be reduced by approximately 5% without changes to the filter material.

Während bei einer von Luft durchströmten Filterpatrone gemäß der EP 1 312 871 B1 im Innenraum des Filterkörpers mit Hilfe von kleinen, zuvor in die Filterpatrone eingebrachten Kugeln aus Polystyrol extreme Turbulenzen in Form einer starken Verwirbelung der Polystyrolkugeln und sogar gelegentlich ein Austritt von einzelnen Polystyrolkugeln aus der Filterpatrone beobachtet wurden, nahmen die Turbulenzen bereits bei der Filterpatrone 46 aus Fig. 10 deutlich ab. Die Polystyrolkugeln wurden dort lediglich noch im unteren Drittel der Filterpatrone 46 verwirbelt. Ein Austritt von Polystyrolkugeln aus der Filterpatrone 46 konnte dort nicht mehr beobachtet werden. Bei den Filterpatronen 46 in den Figuren 7 bis 9 wurde keinerlei Verwirbelung der Polystyrolkugeln mehr beobachtet.While with a filter cartridge through which air flows, according to the EP 1 312 871 B1 In the interior of the filter body, with the aid of small polystyrene balls previously inserted into the filter cartridge, extreme turbulence in the form of a strong swirling of the polystyrene balls and even occasional leakage of individual polystyrene balls from the filter cartridge were observed, the turbulence already occurred with the filter cartridge 46 Fig. 10 significantly. The polystyrene balls were only swirled there in the lower third of the filter cartridge 46. An escape of polystyrene balls from the filter cartridge 46 could no longer be observed there. In the filter cartridges 46 in the Figures 7 to 9 no swirling of the polystyrene balls was observed.

Um eine Beschädigung des zickzackförmig gefalteten und zu einem Hohlzylinder geformten Filtermaterials des Filterkörpers 48 bei der Handhabung der Filterpatrone 46 zu verhindern, ist die in Fig. 11 dargestellte Filterpatrone 46 zusätzlich mit einem als Lochzylinder ausgebildeten luftdurchlässigen Griffschutz 96 versehen, der den Filterkörper 48 in einem geringen Abstand von dessen äußerem Umfang umgibt. Die entgegengesetzten Enden des Griffschutzes 96 sind zusammen mit dem jeweils benachbarten Stirnende des Filterkörpers 48 in der Nut 74 des Deckels 50 bzw. im Deckel 54 vergossen und dadurch fest mit den beiden Deckeln 50, 54 verbunden. Der Griffschutz 96 besteht zweckmäßig aus einem dünnwandigen thermoplastischen Kunststoff, kann jedoch auch aus einem dünnen Metallblech bestehen.In order to prevent damage to the filter material of the filter body 48 when the filter cartridge 46 is handled, the filter material 48 is folded in a zigzag shape and shaped into a hollow cylinder Fig. 11 The filter cartridge 46 shown is additionally provided with an air-permeable handle guard 96 designed as a perforated cylinder, which surrounds the filter body 48 at a short distance from its outer circumference. The opposite ends of the handle guard 96 are cast together with the respectively adjacent end of the filter body 48 in the groove 74 of the cover 50 or in the cover 54 and thereby firmly connected to the two covers 50, 54. The handle guard 96 suitably consists of a thin-walled thermoplastic, but can also consist of a thin metal sheet.

Claims (13)

  1. A filter cartridge (46) for a safety cabinet (10), comprising a hollow cylindrical filter body (48) made of a filter material, which surrounds an interior space (56) in the radial direction, an open cover (50) attached to one end of the filter body (48), which surrounds an inflow opening (70) opening into the interior space (56), and a closed cover (54) arranged at the opposite end of the filter body (48), wherein a projection (86; 92; 94) on the closed cover (54) tapering towards the inflow opening (70) protrudes into the interior space (56), said projection having an inflow surface (90) facing the inflow opening (70) and being rotationally symmetrical and coaxial with a longitudinal central axis (66) of the filter cartridge (46), characterized in that the projection (86; 92; 94) has the shape of a cone with a tip or a slightly rounded tip or the shape of a hemisphere.
  2. The filter cartridge according to claim 1, characterized in that the inflow opening (70) has a nozzle-like flow cross-section which decreases in the direction of the interior space (56).
  3. The filter cartridge according to claim 2, characterized in that the decreasing flow cross-section of the inlet opening (70) is arranged outside the filter body (48).
  4. The filter cartridge according to claim 1, 2 or 3, characterized in that the inlet opening (70) has a boundary surface, which is rotationally symmetrical and coaxial with a longitudinal central axis (66) of the filter cartridge (46) and whose angle of inclination increases in the flow direction of the air through the inlet opening (70).
  5. The filter cartridge according to one of the preceding claims, characterized in that the open cover (50) is formed in one or more parts from a thermoplastic synthetic material.
  6. The filter cartridge according to one of the preceding claims, characterized in that the open cover (50) has an edge flange (60) projecting beyond the outer circumference of the filter body (48) and an annular projection (64) surrounding the inflow opening (70) and projecting axially beyond the side of the edge flange (60) that is facing away from the filter body (48).
  7. Th filter cartridge according to claim 6, characterized in that the annular projection (64) is hollow.
  8. The filter cartridge according to one of the preceding claims, characterized in that the inflow opening (70) is defined at its inner end by a hollow cylindrical web (72) which projects slightly into the interior of the filter body (48) and defines a flat groove (74) which is open towards the filter body (48) and in which the adjacent front end of the filter body (48) is cast.
  9. The filter cartridge according to one of the preceding claims, characterized in that the ratio between the smallest flow cross-section at an inner end of the inflow opening (70) and the largest flow cross-section at an outer end of the inflow opening (70) is less than 0.75 and preferably less than 0.5.
  10. The filter cartridge according to one of the preceding claims, characterized in that the outer diameter of the inflow surface (90) at a foot of the projection (86; 92; 94) facing away from the inflow opening (70) is slightly smaller than the inner diameter of the filter body (48).
  11. The filter cartridge according to one of the preceding claims, characterized in that the height of the projection (86; 92) is less than a quarter of the axial length of the filter body (48).
  12. The filter cartridge according to one of the preceding claims, characterized by an air-permeable grip protection (96) surrounding the filter body (48).
  13. Safety cabinet with at least one filter cartridge (46) according to one of the preceding claims.
EP15000740.9A 2014-03-14 2015-03-12 Filter cartridge for a safety workbench and safety workbench with at least one filter cartridge Active EP2918939B8 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PL15000740T PL2918939T3 (en) 2014-03-14 2015-03-12 Filter cartridge for a safety workbench and safety workbench with at least one filter cartridge

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DE102014003486.0A DE102014003486A1 (en) 2014-03-14 2014-03-14 Filter cartridge for a safety cabinet and safety cabinet with at least one filter cartridge

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EP2918939A1 EP2918939A1 (en) 2015-09-16
EP2918939A3 EP2918939A3 (en) 2015-12-16
EP2918939B1 true EP2918939B1 (en) 2020-05-06
EP2918939B8 EP2918939B8 (en) 2020-07-15

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DE (1) DE102014003486A1 (en)
DK (1) DK2918939T3 (en)
PL (1) PL2918939T3 (en)

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Publication number Priority date Publication date Assignee Title
US8673037B2 (en) 2011-10-18 2014-03-18 Camfil Farr, Inc. Air filter with balanced seal
CN107965849A (en) * 2017-03-09 2018-04-27 中国人民大学 A kind of indoor air cleaning system with inner-outer circulation function
CN110776028A (en) * 2019-12-02 2020-02-11 徐州伊泽瑞智智能设备有限公司 Filter element of intelligent water purifier
JP7428670B2 (en) * 2021-01-21 2024-02-06 株式会社日立産機システム safety cabinet
CN113237181B (en) * 2021-05-27 2022-09-23 江西汇有美智能涂装科技有限公司 Intelligent self-circulation air purification device used after paint spraying

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Publication number Priority date Publication date Assignee Title
GB2261830B (en) * 1991-11-26 1995-07-26 Process Scient Innovations Filter for purification of gas
CA2236517C (en) * 1998-05-01 2000-11-28 Milton Manufacturing Inc. Filter cartridge sealing method
DE10157950C2 (en) 2001-11-20 2003-12-24 Berner Internat Gmbh Safety Cabinet
GB2449846A (en) * 2007-05-29 2008-12-10 Psi Global Ltd A coalescing filter

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Title
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Also Published As

Publication number Publication date
EP2918939A3 (en) 2015-12-16
PL2918939T3 (en) 2020-09-21
EP2918939B8 (en) 2020-07-15
DE102014003486A1 (en) 2015-09-17
DK2918939T3 (en) 2020-07-13
EP2918939A1 (en) 2015-09-16

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